In the architecture of signal processing systems, the rear end of each antenna is connected to a corresponding transmitting/receiving module and phase shifter, wherein the transmitting/receiving module includes radio frequency components such as a low noise amplifier (LNA), a power amplifier (PA) and a power attenuator. The transmitting/receiving module is used for providing power, and the array antenna and the phase shifters are for beamforming, wherein it is important that the system cost can be reduced by the reduction in the number of the transmitting/receiving modules and phase shifters.
It is noted that the conventional system architecture, in which each antenna is connected to a corresponding transmitting/receiving module and phase shifter, is not cost-effective. Specifically, in a conventional array antenna system in which each of radio frequency components antenna is digitally controlled with a corresponding control signal line (which may indicate a set of bit lines in parallel); the array antenna system requires N×M control signal lines and N×M control modules totally if the array antenna system has an array antenna of N antenna units, each antenna unit is connected to M radio frequency components, and N control modules is required for N control signal lines. Such great numbers of control signal lines and control modules not only cause a greater manufacturing cost, but also increase the circuit board real estate. In addition, excessive control signal lines and control modules may also lead to cross-interference between signals, energy loss, and increase difficulty of minimizing manufacturing process.
On the other hand, if the period of a periodic array antenna is overly large, grating lobes will be produced; the grating lobes may consume the energy of the main lobe, and thus degrading the performance of the array antenna, which is the difficulty that frequently occurs in design of array antennas.